Use mapped memory for uploading large textures.

gpu/command_buffer/client/mapped_memory.cc

Index: gpu/command_buffer/client/mapped_memory.cc
diff --git a/gpu/command_buffer/client/mapped_memory.cc b/gpu/command_buffer/client/mapped_memory.cc
index 6d57af4ed57204e62156f215d3af59143b658da7..4332d89f5fdb9b2c554e5cf52d1d0635968d9261 100644
--- a/gpu/command_buffer/client/mapped_memory.cc
+++ b/gpu/command_buffer/client/mapped_memory.cc
@@ -140,4 +140,26 @@ void MappedMemoryManager::FreeUnused() {
   }
 }
 
+void ScopedMappedMemoryPtr::Release() {
+  if (buffer_) {
+    mapped_memory_manager_->FreePendingToken(buffer_, helper_->InsertToken());
+    buffer_ = nullptr;
+    size_ = 0;
+    shm_id_ = 0;
+    shm_offset_ = 0;
+
+    if (flush_after_release_)
+      helper_->CommandBufferHelper::Flush();
+  }
+}
+
+void ScopedMappedMemoryPtr::Reset(unsigned int new_size) {
+  Release();
+
+  if (new_size) {
+    buffer_ = mapped_memory_manager_->Alloc(size_, &shm_id_, &shm_offset_);
+    size_ = buffer_ ? new_size : 0;
+  }
+}
+
 }  // namespace gpu